Symbols of strength and determination, bison are Ice Age survivors. Clearing away snow and brush with their massive heads, they weigh up to 2,000 pounds and can run up to 40 miles per hour. Once numbering 30-60 million in North America, their numbers were decimated in just a few decades as expansion pressed westward. No other species on Earth has declined so quickly. Several Native American tribes are working with WWF to grow bison numbers once again across vast grasslands under their management.

They may not be household names, but these ecosystems are vital to the health of our planet. They support an incredible range of plants and animals, as well as millions of people and their communities, and play a critical role in fighting climate change.

Why They Matter

Historically bison were the dominant grazer on the Northern Great Plains landscape. This dominance shaped the landscape by affecting the pattern and structure of the grasses and vegetation that grew. Expansive areas of native grasslands allowed animals to flourish along with many species of other prairie wildlife.

Threats

Population
20,504

Extinction Risk
Near Threatened

EX

Extinct

No reasonable doubt that the last individual has died

EW

Extinct in the Wild

Known only to survive in cultivation, in captivity or as a naturalised population

CR

Critically Endangered

Facing an extremely high risk of extinction in the Wild

EN

Endangered

Facing a high risk of extinction in the Wild

VU

Vulnerable

Facing a high risk of extinction in the Wild

NT

Near Threatened

Likely to qualify for a threatened category in the near future

LC

Least Concern

Does not qualify for Critically Endangered, Endangered, Vulnerable, or Near Threatened

Habitat Loss

The plains bison is the largest land mammal in North America with some adult bulls weighing in excess of 2,000 lbs. Tens of millions of these iconic animals once roamed across much of North America. Today, the largest remaining wild herd of approximately 4,500 individuals can be found in Yellowstone National Park. Large North American grazers including the plains bison traditionally roamed across millions of acres, which kept the grasslands and herds healthy and diverse. However, early settlement and current land uses by present day communities have redefined where these large animals are able to roam. WWF’s Northern Great Plains Program is working with National Parks, native tribal communities, and its ranching partners to find common ground on returning bison to suitable intact prairie landscapes.

Genetics

An overall population of just over 20,000 bison managed as wildlife in North America and small herd size among them contributes to ongoing loss of genetic diversity. Therefore long-term conservation of existing diversity is at risk. Early 20th century experiments to interbreed bison and cattle with the goal of producing heartier livestock has also had an impact on population viability. At present, there are only believed to be two public bison herds that have not shown evidence of interbreeding with cattle to date; Yellowstone NP, and Elk Island National Park in Canada. Conservation groups have been working hard to establish additional herds elsewhere to safeguard these valuable genetics should a catastrophic event (e.g. disease outbreak) threaten these source herds.

Social & Political Support of Bison Reintroduction

A limited constituency for public bison herds in rural regions of the plains where opportunities for restoration on intact grasslands at scale are most feasible makes a universal strategy for reintroduction challenging. In addition, there is narrow support for restoring bison as wildlife within the sporting community because broad exposure to bison as wildlife has been limited over the past century. Both affect progress in the political arena. For this reason WWF seeks opportunities with partners and communities who embrace the reintroduction or expansion of bison populations including Tribes and National Parks.

What WWF Is Doing

WWF is identifying opportunities and creating places where bison can thrive in large herds (numbering over 1000 bison) on vast landscapes in the Northern Great Plains, the heart of the plains bison’s historic range. We are partnering with the Oglala Lakota to create the nation’s first tribal national park and restore a herd of bison to ancestral homelands. We work with Fort Peck Reservation, Fort Belknap Reservation, and Yellowstone National Park to conserve the genetically important bison from the Park by supporting the movement of animals into new landscapes where they are welcome. We also engage in research and public outreach activities aimed at reminding the American public why bison, symbols of strength and determination, are so critical to the restoration of the American prairie.